Shell mold stripping mechanism



Oct. 7, 1958 P. KLAMP sHELL MOLD STRIPPING MECHANISM Filed May 2, 1955 3Sheets -Sheet 1 in! flrnku ivllli.

INVENTOR. P1904 KAHMP 0d. 7, 1958 P; K M 2,854,711

SHELL MOLD STRIPPING. MECHANISM Filed ma 2, 1955 s sheets-sheet; 3

11v V EN TOR. PA U4 K4 AM P United States SHELL MOLD STRIPPING MECHANISMPaul Klamp, Detroit, Mich., assignor to Mechanical Handling Systems,Inc., Detroit, Mich, a corporation of Michigan Application May 2, 1955,Serial No. 505,291

8 Claims. (Cl. 22-34) This invention relates to improved mechanism forstripping or removing a formed shell mold from a pattern surface whichis supported by a pattern carrier.

In accordance with known practice, the pattern carrier is equipped witha stripper plate, supported by the carrier for movement relativethereto, and a number of stripper pins are carried by the stripper platefor movement through holes provided in the pattern. Conventionalpractice also provides some actuating device for moving the stripperplate in an ejection cycle toward the pattern carrier to project thestripper pins through the holes in the pattern and lift the mold fromthe pattern surface. This actuating device will be termed a knockoutmember, and upon movement of the knockout member in the oppositedirection to complete the ejection cycle, the stripper plate moves awayfrom the pattern carrier and the stripper pins are withdrawn to a normalposition where their ends lie flush with, or slightly below, the surfaceof the pattern.

The present invention provides a new relationship between theseconventional elements, particularly with respect to the relation betweenthe knockout member and the remaining structure. Means are provided,responsive to movement of the knockout member, for positively placingand maintaining the stripper plate in its normal or retracted positionand for positively moving the stripper toward and away from the patterncarrier during the ejection cycle.

As the foregoing conventional elements are related in the presentinvention, the normal or retracted position of the stripper platerelative to the pattern carrier is established and maintained bypositioning means which act to prevent movement of the stripper platetoward the pattern carrier. Preferably, guide pins are incorporated aspart of the stripper plate assembly, these guide pins being slidable inguide surfaces of the pattern carrier to define the direction ofrelative movement between pattern carrier and stripper plate. Thispermits the stripper pins to function solely for the removal of a mold.In the preferred construction, the guide pins also serve to limitmovement of the stripper plate away from the pattern carrier so that theguide pins, in combination with the positioning means act to positivelydefine the normal or retracted position of the stripper plate andstripper pins carried thereby.

Release of the positioning means to permit the stripper pins'to beprojected through the pattern plate is arranged so as to be in responseto movement of the knockout member. As the knockout member approachesthe stripper plate, the positioning means are released to permitmovement of the stripper plate with the knockout member. Likewise, asthe knockout member moves away from the stripper plate the positioningmeans are reengaged to lock the stripper plate in its normal position.In the preferred construction, the means employed to accomplish thisoperation include a positioning member pivotally supported by thepattern carrier and mounting a latch surface engageable with acooperating surface on 2,854,711 Patented Oct. 7, 1958 the stripperplate. A suitable shaped cam track is formed on this pivotally mountedpositioning member, this cam track being engageable by a followercarried by the knockout member to thereby produce movement of thepositioning member about its pivotal axis between engaged and releasedpositions in response to relative movement between the knockout memberand the pattern carrier.

During the ejection cycle the stripper plate is positively secured tothe knockout member to insure withdrawal of the stripper plate fromejecting to normal position and the re-engagement of the positioningmeans which accompanies such withdrawal. This is accomplished bylatching means for connecting the stripper plate to the knockout member,these latching means being operable also in response to relativemovement between the knockout member and the pattern carrier. As theknockout member approaches the pattern carrier and shipper plate, thelatching means are engaged with the stripper plate in response to suchmovement, and released from the stripper plate in response to movementof the knockout member away from the pattern carrier after the stripperplate has been returned to its normal retracted position and thepositioning means engaged for maintaining that position. Preferably, thelatching means for so securing the knockout member to the stripper platecomprises latch members pivotally carried by the knockout member andactuatable by engagement with cam surfaces carried by the patterncarrier, this engagement serving to move the latch members into contactwith latch surfaces on the stripper plate.

The construction of the invention thus provides for positive location ofthe stripper plate and stripper pins in a normal position so that nodeformation of the mold being formed can result from relative movementbetween the stripper plate and pattern during any motion imparted to thepattern carrier during the mold forming and curing cycles. The inventionalso provides for positive movement of the stripper plate toward andaway from the pattern carrier during the ejection cycle. For a givensize of the component parts, a greater extent of movement of thestripper pins can be obtained by the positive movement of the stripperplate both toward and away from the pattern carrier, than can beobtained by employing springs for returning the stripper pins and plateto normal position. All operations and movements result from relativemovement between the knockout member and the pattern carrier, and thuscan only take place during the ejection phase of the cycle of a moldforming operation.

Other features and advantages of the invention will be brought out inconjunction with the detailed description to follow of a presentlypreferred embodiment thereof. This embodiment is illustrated in theaccompanying drawings which comprise the following views:

Fig. l, a side elevation of the major components of the invention,comprising a pattern carrier, pattern plate, stripper plate and pins,and a knockout member movable relative to the pattern plate;

Fig. 2, a side elevation of the structure of Fig. 1 taken in thedirection of the arrow 2 of Fig. 1;

Fig. 3, an elevation on an enlarged scale taken in the direction of thearrows 33 of Fig. 2, showing one of the positioning members whichprevent movement of the stripper plate toward the pattern carrier. Inthis view, the knockout member is shown displaced from the position ofFigs. 1 and 2 and approaching contact with the stripper plate;

Fig. 4, a plan view taken along the lines 44 of Fig. 3;

Fig. 5, a fragmentary plan view taken along the line 5-5 of Fig. 2; and

Fig. 6, a sectional elevation taken along the lines 6-6 of Fig. 2showing the means for latching the knockout member to the stripper platein engaged position therewith.

Referring to Figs. 1 and 2, the main component parts there shown includea pattern carrier supporting the pattern plate 11 (Fig. 1), a stripperplate 12 carrying a number of stripper pins 13, and a knockout member orplate 14' which is mounted on the end of the rod 15 of a fluid pressureactuating cylinder assembly 16.

The remaining structure of a specific machine has not been included inthe present disclosure because of the obvious fact that the ejectionmechanism which forms the subject matter of the present application isnot confined in use to a specific machine. For the same reason, fulldetails of the construction of the pattern carrier 10 have not beenincluded herein. However, this pattern carrier is similar inconstruction, except for features which contribute to the operation ofthe ejection mechanism of the present invention, to the pattern carrierdisclosed in the copending application of Paul Klamp and Leonard 1.Bishop, Serial No. 299,606, filed May 18, 1953, and entitled TurntableType Machine for Forming Shell Molds.

This pattern carrier 10 consists in a generally rectangular framework inwhich the pattern plate 11 is removably supported. A boss 18 is providedat each corner of this rectangular framework, each boss being internallydrilled and counterbored to provide guide surfaces which slidablyreceive a guide pin 19, having a headed end 20 engaging the.counterbore, and a threaded end 21 for attachment to the stripper plate12. Engagement between the headed end 20 of the guide pin 19 and theshoulder 22 at the bottom of the counterbore limits movement of thestripper plate away from the pattern carrier.

. Each stripper pin 13 is dimensioned so that its free end 23 lies flushwith, or slightly below, the pattern forming surface 24 of the pattern11 when the headed end 20 of the guide pin 19 is in engagement with theshoulder 22.

The stripper plate 12 also is a generally rectangular member, conformingroughly to the size and configuration of the pattern carrier 10 andpattern 11. Ordinarily the stripper plate will be provided with rows ofholes within any of which a stripper pin 13 can be selectivelypositioned so that the same stripper plate can be employed inconjunction with a number of different patterns.

When the pattern carrier 10 is in a horizontal position as shown, thestripper plate is suspended therefrom "by the engagement between thehead ends 20 of the guide pins 19 and the shoulders 22 within each ofthe bosses 18.

The means for maintaining the stripper plate 12 in this position exceptduring the ejecting cycle, limit movement of the stripper plate towardthe pattern carrier, and comprise a pair of positioning arms 26, each ofwhich is pivotally attached to a portion 27 of the pattern carrier.structure by a pivot pin 28. The arms 26are each free to swing aboutits pivot pin 28. Each arm carries a latch member 29 (Fig. 3) secured tothe arm by a bolt 30 (Fig. 1). Each arm is also provided with a camtrack 32 for controlling the position of the arm about its pivot pin 28in a manner to be soon described.

A pair of latch buttons 34 are secured to the stripper plate 12, eachproviding a surface 35 adapted to be con tacted by a latch member 29when the parts are in the position shown in Figs. 1 and 3. Each latchbutton 34 is mounted in a manner so as to be adjustable relative to the.stripper plate 12.

The knockout member 14 also consists of a rectangular p'late suitablyconnected to the end of the rod 15 of the actuating cylinder assembly16. A guide arm 36 is secured to the knockout plate and projects fromone side thereof (see Figs. 2 and 5). A guide block 37 is secured to theprojecting end of the arm 36, as shown in Fig. 5 and this guide block 37rides between a pair of vertical angle members 38 which are spaced toform a vertically 4 extending guide slot 39. This keeps the knockoutplate 14 and rod 15 from rotating in the actuating cylinder 16 andmaintains the knockout plate in proper alignment with the stripper plateand pattern carrier.

A pair of cylindrical cam followers 40 are each mounted on a smallpedestal member 41 secured to the knockout plate 14. Each follower 40projects laterally a slight distance beyond one edge of the knockoutplate, as shown in Fig. 2. Also, as shown in Fig. 3, the position ofeach cam follower 40 is such that it will engage the cam track 32 of oneof the positioning arms 26 as the knockout plate is moved verticalytowards the pattern carrier.

In order to produce positive movement of the stripper plate in eitherdirection toward or away from the pattern carrier in response tocorresponding movement of the knockout plate, means are provided forlatching the stripper plate and knockout plate together. These meansinclude a pair of latch members 44. Each latch member 44 is attached bya pivot pin 45 to a suitable supporting member 46 secured to theunderside of the knockout plate 14 as by screws 47 (see Fig. 1). Eachlatch member 44 is formed with two arms 48 and 49, positioned at rightangles to each other. The pivot pin 45 engages a hole formed in the arm48, which underlies the surface of the knockout plate 14 when the partsare assembled. The other arm 49 projects generally upwardly above thesurface of the knockout plate 14. A latch block 5% is mounted on theupper surface of the knockout plate 14 adjacent the arm 49 of each latchmember 44. These blocks 50 have two functions; one, to contact theunderside of the shipper plate when the knockout plate is movedupwardly; the other, to prevent the arm 49 of each latch member fromfalling over out of working position onto the top of the knockout plate14. Such working position is also established by engagement between atapered surface 51 on the arm 48 of each latch member with the undersurface 52 of the knockout plate 14 (see Fig. 6). A V-shaped nose .54 isprovided on the arm 49 of each latch member, and complementary surfacesare formed on the edge of the stripper plate 12 at 53. Also mounted onthe arm 49 of each latch member is a roller follower 55 which is adaptedto contact a cam 56 secured to the structure of a pattern carrier, asshown in Fig. 1.

After a mold has been formed and cured on the pattern 11, the ejectioncycle is initiated, fluid pressure being admitted to the actuatingcylinder assembly 16 .to produce upward movement of the knockout plate14, from the position shown in Figs. 1 and 2, toward the pattern carrier10 which is held, in the conventional manner, in the horizontal positionillustrated by means not shown. This movement of the knockout member 14relative to the pattern carrier results first in the follower members 49on the knockout plate engaging the cam tracks 32 of the positioning arms26, and movement of the knockout plate into contact with the stripperPlate is accompanied by pivotal movement of the positioning arms 26,clockwise as these parts are viewed in Figs. 1 and 3, to move the latchmember 29 of each arm 26 out of engagement with the latch button 34 ofthe stripper plate. This pivotal movement of the positioning arms 26 isproduced by the first segment 62 of the cam track 32. The remainingsegment of the cam track morely acts to hold the positioning arms 26 outof latched position while the stripper plate is moved toward and awayfrom the pattern carrier in the injection cycle.

During the last portion of pivotal movement .of the arms 26, the rollerfollower 55 on each latch member 44 comes into contact with the taperedsurface 57 at the end of each cam member 56. Further upward movement ofthe knockout plate is accompanied by pivotal movement of each latchmember, as the roller follower 55 thereof moves along the surface 57 ofthe cam members 56, bringing the latch surface 58 on the nose 54 ofeachlatch member into engagement with the correspondingly formed surface59 on the stripper plate. Simultaneously, the latch blocks 58 on theknockout plate are coming into contact with the under surface of thestripper plate. The parts are held in latched engagement during furtherupward movement of the knockout member, as the roller followers 55 ridealong the vertical straight surface 60 of each cam member 56.

After the knockout plate and stripper plate have been moved toward thepattern carrier to the extent desired for proper ejection of the moldfrom the pattern, the direction of movement of the knockout plate isreversed. During the first portion of this return movement, the stripperplate 12 and its stripper pins 13 are positively withdrawn from thepattern carrier by the latched engagement between the stripper plate andknockout plate. The parts are dimensioned so that as the head ends 20 ofthe guide pins 19 come into contact with the shoulders 22 in the guidebores, the roller follower 55 of each latch member reaches the taperedend surface 57 of its cam 56. Contact between the head ends of the pins19 and the shoulders 22 arrest further withdrawing movement of thestripper plate and stripper pins. The tapered surfaces 58 and 59 of thelatch members 44 and stripper plate 12, respectively, produce a pivotalreleasing movement of the latch members in response to furtherwithdrawing motion of the knockout plate. Simultaneously, the followers40 have reached the actuating segment 62 of the cam track 32 of eachpositioning arm 26, producing a pivotal movement thereof to bring thelatch member 29 back into engagement with the latch button 34. Thus, asknockout plate separates from the stripper plate the latter is locked inposition relative to the pattern carrier.

From the foregoing it can be seen that all movements of the stripperplate and associated latching devices occur in response to movement ofthe knockout plate. This means that no movement of the stripper platecan take place except during the knockout cycle of operation of the moldforming machine. Consequently, no damage to a mold being formed canresult by displacement between the stripper plate and pattern carrier.

Likewise, the arrangement of movement in response to knockout platemovement is accomplished with relatively simple structure that iscompletely positive in action.

Changes and modifications to the specific structure shown and describedare to be considered a practice of the present invention if embracedwithin the scope thereof as defined in the following claims.

I claim:

1. Mechanism for stripping a shell mold from a pattern, supported by apattern carrier, by movement of a stripper plate and stripper pins froma normal position where the stripper pins do not project above thepattern surface to an ejecting position where the stripper pins areprojected above the pattern surface through holes therein, characterizedby means suspending said stripper plate from said pattern carrier formovement relative thereto between said normal and ejecting positions,releasable positioning means interposed between said pattern carrier andstripper plate for normally preventing movement of said stripper platetoward ejecting position, a knockout member and means for moving saidknockout member toward and away from said pattern carrier in an ejectioncycle, and means for releasing said positioning means in response tomovement of said knockout member toward said pattern carrier.

2. Mold stripping mechanism as set forth in claim 1 furthercharacterized by the provision of latch means for securing said knockoutmember to said stripper plate during movement of said stripper platetoward and away from said pattern carrier. I

3. Mold stripping mechanism as set forth in claim 2 wherein said latchmeans comprise a latch member pivotally supported by said knockoutmember, a latch surface on said stripper plate adapted to be engaged bysaid latch member, and a latching cam carried by said pattern carrierfor producing engagement between said latch member and latch surface inresponse to relative movement of said knockout carrier toward saidpattern carrier and for releasing said latch member from said latchsurface in response to movement of said knockout member away from saidcarrier.

4. Mold stripping mechanism as set forth in claim 1 wherein saidpositioning means comprise a positioning member pivotally secured tosaid carrier, latch surfaces provided on said member and on saidstripper plate, said releasing means producing pivotal movement of saidpositioning member from a latched to an unlatched position of said latchsurfaces in response to relative movement between said knockout memberand said carrier.

5. Mold stripping mechanism as set forth in claim 4 wherein saidreleasing means for producing pivotal movement of said positioningmember include a cam surface formed thereon and a cam follower carriedby said knockout member.

6. Mechanism for stripping a shell mold from a pattern, supported by apattern carrier, by movement of a stripper plate and stripper pins froma normal position where the stripper pins do not project above thepattern surface to an ejecting position where the stripper pins areprojected above the pattern surface through holes therein, characterizedby means suspending said stripper plate from said pattern carrier formovement relative thereto between said normal and ejecting positions,said suspending means acting to define said normal position, releasablepositioning means interposed between said pattern carrier and saidstripper plate for normally preventing movement of said stripper platetowards ejecting position, a knockout member and means for moving saidknockout member between normal and ejecting positions in an ejectingcycle, means for releasing said positioning means in response tomovement of said knockout member toward said stripper plate into contacttherewith, and means for latching said knockout member to said stripperplate in contact therewith during movement of said stripper plate fromnormal to ejecting position and return.

7. In mechanism for stripping a shell mold from a pattern which includesa pattern carrier, a reciprocable knockout member and a stripper platemember movable to and from the pattern in a mold ejection cycle whencontacted by the knockout member, the combination of a latch carried byone of said members and normally biased to unlatched position, a latchsurface provided on the other of said members for engagement by saidlatch, and means for engaging said latch with said latch surface inresponse to movement of said knockout member toward said pattern carrierduring the mold ejection cycle of movement of said stripper plate, saidlatch engaging means comprising a fixed latching cam positioned to becontacted by said latch as the knockout member contacts the stripperplate, said cam having an initially contacted surface for causingmovement of said latch to engaged position and a continuing surface forholding said latch in engagement during the mold ejection cycle ofmovement.

8. A mold stripping mechanism according to claim 7 wherein said latchcam is fixedly supported by said pattern carrier.

References Cited in the file of this patent UNITED STATES PATENTS2,669,759 Valyi Feb. 23, 1954 2,691,195 Daugindas Oct. 12, 1954

